This invention is related generally to the field of cutting of graphics areas or the like from sheets for various purposes, and other narrow-path-processing with respect to graphics areas on sheets.
The technical field involving the cutting of graphic areas from sheets, or otherwise doing narrow-path-processing with respect to graphics images on sheets, includes, for example, the face-cutting of laminate sheets to form decals. More specifically, a graphics image area on the face layer of a laminate needs to be cut away from the remainder of the face layer so that the graphics area (decal) can subsequently be pulled away from the backing layer of the laminate and be applied elsewhere as intended. Highly accurate face-layer cutting about the graphics is obviously highly desirable.
This is but one example in which highly accurate sheet cutting (or other processing) is desirable. In many other situations, highly accurate sheet cutting which is desired may not involve face-cutting, but through-cutting, in which the full thickness of the sheet is cut about a graphics area on the sheet. And in many situations, rather than highly accurate cutting, highly accurate scoring, creasing, line embossing or the like, in each case, of course, along a line the varying direction of which is determined by the shape of the graphics area. Together these types of operations on sheets with respect to graphics areas thereon are referred to herein for convenience as xe2x80x9cnarrow-path-processing.xe2x80x9d For convenience, the prior art problems and the invention herein which solves such problems will be discussed primarily with reference to sheet-cutting apparatus.
A method and associated apparatus which addresses many of the problems encountered in such processing of sheet material is the i-cut(trademark) vision cutting system from Mikkelsen Graphic Engineering of Lake Geneva, Wis., and is the subject of U.S. patent application Ser. No. 09/678,594, filed on Oct. 4, 2000, and U.S. patent application Ser. No. 09/827,000, filed on Apr. 5, 2001, and U.S. patent application Ser. No. 09/951,167, filed on Sep. 13, 2001.
The invention described in Ser. No. 09/678,594 is a method and apparatus for achieving highly improved accuracy in cutting around graphics areas in order to fully adjust for two-dimensional distortion in the sheets from which the graphics areas will be cut, including distortion of differing degrees in different directions on the sheet of material. The distortion may be from the printing process or from some other post-printing process such as material handling or during the cutting process itself This invention also provides improved speed and accuracy in narrow-path-processing and greater efficiency of material usage.
The invention described in Ser. No. 09/827,000 is a method and apparatus for automatically and rapidly determining the position and orientation of a sheet of material on a work surface. When the placement of the sheet of material is not precisely controlled, the speed of the cutting or other narrow-path-processing system is often impaired because the system may require manual intervention to adjust the placement of the sheet of material so that the system can begin processing. Thus, the invention described in such patent disclosure provides further improved speed over the invention described in the first-mentioned patent disclosure.
The invention described in Ser. No. 09/951,167 is a method and apparatus which further improves the speed and efficiency of narrow-path-processing by automatically correcting for careless initial manual placement or malfunctioning automatic placement of a sheet of material on a work surface. The invention automatically and rapidly finds a set of special marks used for determination of the position and orientation of the sheet of material, eliminating the need for yet another possible manual intervention step.
In some cases, such as in the i-cut(trademark) system from Mikkelsen Graphic Engineering, a flatbed plotter is used. These are devices having a positionally-controlled cutting implement above a flat work surface on which the sheet to be cut rests. The cutting implements are controlled based on controller-supplied instructions based on the X-Y coordinates necessary to achieve cutting along the intended path, such as about the graphics area.
Achieving greater speed and overall efficiencies in cutting or other narrow-path-processing is a continuing challenge encountered in the field of graphics image processing. One measure of efficiency is the speed with which sheets are processed. A source of inefficiency is the length of time required by the system to begin the cutting process after the sheet of material on which graphics areas have been previously printed are placed on the work surface of the cutting apparatus, either manually or by automatic sheet-feeding equipment. In either of these set-up situations, the cutting apparatus must determine the position and orientation of the sheet on the work surface in order to proceed accurately with the cutting process. If the operator or automatic sheet-feeder places the sheet of material on the work surface such that it is outside of the area or region of alignment on the work surface which the cutting system expects to find the sheet, manual intervention may be necessary to adjust the placement of the sheet to within the required initial region in order for the process to continue beyond this initial set-up step. A further source of inefficiency is the time-consuming step which may be required to allow the system to determine the initial position and orientation of the sheet on the work surface.
Another measure of efficiency is the amount of material waste which is produced during narrow-path-processing. Depending on volumes of material processed and the cost of the material used, the amount of waste may be important to minimize in order to increase overall process efficiency.
Despite the significant advances represented by the i-cut(trademark) system, further increases in efficiency (speed of operation and material usage) are highly desirable in automated cutting systems.
It is an object of this invention to provide an improved method and apparatus for precision cutting of graphics areas from sheets overcoming some of the problems and shortcomings of the prior art.
Another object of this invention is to provide an improved method and apparatus which increases the speed of cutting and other narrow-path-processing of sheet material.
Another object of this invention is to provide an improved method and apparatus which reduces material waste in cutting and other narrow-path-processing of sheet material.
Another object of this invention is to provide an improved method and apparatus which automate the cutting and other narrow-path-processing of sheet material as much as possible.
Another object of this invention is to provide a method and apparatus for reducing the time to determine sheet position and orientation in apparatus for precise cutting around graphics areas.
Still another object of this invention is to provide an improved method and apparatus for cutting and other narrow-path-processing with respect to graphics on sheet materials of various kinds.
These and other objects of the invention will be apparent from the following descriptions and from the drawings.
The instant invention overcomes the above-noted problems and shortcomings and satisfies the objects of the invention. The invention is an improved method and apparatus for cutting graphics areas from sheets, or other narrow-path-processing with respect to graphics images. Stated more broadly, the invention is an improved method and apparatus for narrow-path-processing with respect to graphics images on sheets, including by cutting, creasing, scoring or the like around such images. Of particular note is that the instant invention brings high speed and improved efficiency, including minimizing material waste and eliminating certain manual intervention, to the precision cutting of graphics images from sheets bearing such images, including without limitation in situations in which there has been distortion of various kinds in the sheets, including two-dimensional distortion.
The method of this invention is stated with respect to cutting at least one graphics area from a sheet of material bearing a combination of such graphics area(s) and a plurality of registration marks in predetermined positions with respect to the graphics area(s), such combination being in a predetermined approximate position and orientation with respect to a set of reference features of the sheet.
The method is of the type which includes (a) placing the sheet on a sheet-receiving surface, (b) sensing the precise positions of the marks with a main sensor, and (c) cutting the graphics area(s) from the sheet in response to such precise positions. The invention includes the addition of steps which automatically enable the process to proceed regardless of whether or not the sheet has been placed in an expected position and orientation on the sheet-receiving surface. These steps include determining whether the reference features are in an expected coordinate region on the sheet-receiving surface. If the reference features of the sheet are not in the expected coordinate region, the coordinate region of the reference features is automatically determined. Further additional steps include sensing the metrics of the reference features to determine the position and orientation of the sheet and inferring therefrom the approximate positions of the registration marks.
The coordinate region of the set reference features on the sheet-receiving surface is the area thereof which, when contained within the field of view of the main sensor, enables main-sensor sensing of the set with precision sufficient to determine the position and orientation of the sheet of material on the sheet-receiving surface such that the various registration marks can be automatically found to enable subsequent precision sensing thereof
In certain preferred embodiments of the invention, automatically determining the coordinate region of the reference features includes moving the main sensor in a predetermined pattern surrounding the expected location of the set of reference features and stopping the movement of the main sensor when the coordinate region of the set is located within the field of view of the main sensor. In one such embodiment, movement of the main sensor is in the plane of the sheet-receiving surface. In another such embodiment, moving the main sensor includes rotating the main sensor such that the field of view changes.
In certain embodiments of the invention, the automatic determining step includes enlarging the field of view of the main sensor, thereby locating the coordinate region of the set of reference features within an enlarged field of view. The main sensor is then repositioned, including shrinking the field of view of the main sensor, such that the set is within the field of view of the main sensor. In one such embodiment, enlarging and shrinking the field of view of the main sensor is performed by zooming a lens of the main sensor. In another such embodiment, the enlarging and shrinking steps are performed by increasing and decreasing respectively the distance between the main sensor and the sheet-receiving surface.
In another embodiment of the invention, automatically determining the coordinate region of the reference features includes locating the reference features within the field of view of a secondary sensor.
In a preferred embodiment of the invention, automatically determining the coordinate region of the reference features includes sensing an edge of the sheet.
In a highly preferred embodiment of the invention, automatically determining the coordinate region of the reference features includes sensing an adjacent pair of edges of the sheet.
In another embodiment of the invention, automatically determining the coordinate region of the reference features includes sensing a predefined graphics feature of the sheet.
In another embodiment of the invention, automatically determining the coordinate region of the reference features includes sensing two predefined graphics features of the sheet.
The inventive apparatus is a device for cutting at least one graphics area from a sheet of material bearing a combination of such graphics area(s) and a plurality of registration marks in predetermined positions with respect to the graphics area(s). The combination is in a predetermined approximate position and orientation with respect to a set of reference features of the sheet. The device includes: a sheet-receiving surface; a main sensor; a cutter operatively connected to the sensor and movable about the sheet-receiving surface for cutting the graphics area(s) from the sheet of material in response to the precise positions of the marks sensed by the main sensor; a reference feature identifier which, if the reference features are not in an expected coordinate region on the sheet-receiving surface, automatically determines the coordinate region of the reference features, and which, when the coordinate region of the reference features is known, senses the metrics of the reference features in order to infer the approximate positions of the registration marks.
As used herein, the term xe2x80x9cmetrics,xe2x80x9d applied in characterizing a reference feature, refers to the numerical parameters which can be used by the device to describe the position and orientation of the reference feature and, in combination with other metrics of this and other reference features, can be used to infer the position and orientation of the sheet of material on the sheet-receiving surface. For example, a straight edge of a sheet of material defines a line which lies at an angle with respect to the coordinate system axes of the sheet-receiving surface. Such angle is one such xe2x80x9cmetric.xe2x80x9d The comer of a sheet defined by the intersection of two such edges defines a point within the coordinate system, and the x, y coordinates of the comer point are two more such xe2x80x9cmetrics.xe2x80x9d Other metrics might include, among other things, certain geometric descriptors of shapes, positions, and orientations of graphical images within the graphics area itself
In highly preferred embodiments of the inventive apparatus, the reference feature identifier includes a controller with a set of locating instructions for moving the main sensor in a predetermined pattern surrounding the expected coordinate region of the reference features, and stopping the movement of the main sensor when the reference features are located within the field of view of the main sensor.
In certain preferred embodiments of the invention, the reference feature identifier includes a zoom lens on the main sensor and a controller with a set of locating instructions for (a) enlarging the field of view of the main sensor by zooming the lens, (b) locating the reference features within the enlarged field of view, (c) repositioning the main sensor in response to the locating step, and (d) shrinking the field of view of the main sensor by zooming the lens such that the reference features are within the field of view of the main sensor.
In another embodiment of the inventive apparatus, the reference feature identifier includes a main-sensor height adjustor and a controller with a set of locating instructions for (a) enlarging the field of view of the main sensor by increasing the distance of the main sensor from the sheet material, (b) locating the reference features within the enlarged field of view, (c) repositioning the main sensor in response to the locating step, and (d) shrinking the field of view of the main sensor by decreasing the distance of the main sensor from the sheet such that the reference features are within the field of view of the main sensor.
In certain embodiments of the invention, the reference feature identifier includes a secondary sensor with a field of view larger than the field of view of the main sensor and a controller with a set of locating instructions for (a) locating the reference features within the field of view of the secondary sensor, and (b) repositioning the main sensor in response to the locating step such that the reference features are within the field of view of the main sensor.